JPS58202993A - Welding wire rod of stainless steel - Google Patents

Abstract

PURPOSE:To stabilize a welding arc and to form a weld bead having an excellent shape, by using an Ni-Cr-Fe wire rod contg. Si, Mn in a specific ratio and further contg. a small amt. of S and O as a welding wire rod for Ni-Cr stainless steel. CONSTITUTION:An Ni-Cr-Fe alloy wire rod contg. <0.20% C, 0.30-1.50% Si, 1.10-2.60% Mn, 6-25% Ni, 12-32% Cr, 0.008-0.050% S, 0.0050-0.040% O, <0.06% N, and 1.3-8.0 Mn/Si value is used as a welding wire rod to be used in welding of Ni-Cr stainless steel. Or the alloy wire further contg. <=7% >=1 kinds among <5% Mo, <5% Cu, <1% Nb, <1% Ti or <=0.5% at least 1 kind among B, Ca, Mg, rare earth elements or contg. the same in combination is used. The weld bead having high quality is formed with the stable welding arc.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a stainless steel welding wire rod, in particular Ni-0r which has excellent weldability and can obtain a high quality welded part.
-It relates to Fe-based stainless steel welding materials.

As is well known, Ni- such as 5US304.8U8816
Since 0r-Fe stainless steel has excellent performance such as corrosion resistance and heat resistance, it is widely used as a material for chemical equipment, heat resistant equipment, atomic couplants, etc. Naturally, these devices are assembled by welding because airtightness and watertightness are important, but welding materials used to weld such materials are Conventionally, Ni-0r such as Y2O2
-Fe-based stainless steel welding wires have been used.

However, conventionally commercially available Ni-0r-F
E-series stainless steel welding materials have the following problems: (1) The bead shape is poor and the bead is convex. (2) The stability of the welding arc is poor. (3) The slag is difficult to peel off at the welded part. Due to these drawbacks, defects such as (a) poor fusion, (b) generation of protrusions, and (C) slag entrainment occur in the weld, and as a result, the desired weld performance cannot be achieved. However, there was a major problem in that the welded portion required a large amount of man-hours for rework by machining, grinding, etc.

Therefore, various studies have been carried out in various fields regarding the improvement of arc stability and bead shape.
Efforts have been made to improve the welding machine by developing a pulse welding machine, and even reviewing the shielding gas, but the above-mentioned problem has not yet been completely solved. In addition, no solutions have been proposed to date for improving the slag removability of welds.

In view of these circumstances, the present inventors have developed a Ni-Cr-Fe stainless steel welding wire that has a good bead shape, excellent welding arc stability, and has a small amount of slag and good slag removability. As a result of studying the effects of various alloying elements, we found that the bead shape under downward welding conditions was significantly improved by adding S (sulfur) and O (oxygen) in addition to the well-known additive element Si. I discovered that. In particular, M, n (manganese) and 8i (
When the ratio of the amount of silicon (silicon) is regulated within a predetermined range, the addition effect is recognized even with the addition of a very small amount of 8.
Combined with the combined addition of O, the bead shape and blowhole resistance in all welding positions were clearly improved.
For example, they discovered a fact that can be recognized without impairing corrosion resistance. The present invention has been completed based on these findings.

That is, in the present invention, in terms of weight, C: α20 cm or less, si
:α80~1.50%, Mn:1.10~2.60%
, Ni; fiO~2&0%, Cr:12.0~
32.0%, S: αoos to α050%, 0: α005
0 to 0040%, N: 006%, and Mn
The present invention is characterized by a stainless steel welding wire having an excellent weldability in which the /Si content ratio is within the range of 1.8 to aO, and the balance is Fe and unavoidable impurities. With this configuration, it has become possible to obtain a welded part with an excellent bead shape, good welding arc stability, and improved blowhole resistance.

Furthermore, in the present invention, at least one of B, Ca, Mg, and rare earth elements (REM), which have been considered to cause instability of the welding arc, can be added to the welding wire rod having such a composition. Further, by further containing 0.05 mm in a proportion not exceeding 0.05 mm, it is possible to reduce the generation of slag without impairing the corrosion resistance or bead shape of the weld, and to further improve the slag removability. It was.

Here, C (carbon) contained in the welding wire rod according to the present invention is contained in order to stabilize the austenitic structure of the welded part and improve its strong earthquake resistance, and generally its content is The amount is 0.
20% or less (same as weight standard), preferable ((α06%
Hereinafter, the ratio is more preferably maintained at 0.008 cm or less. It should be noted that if the content of C is too large, the corrosion resistance of the welded part will deteriorate, causing problems such as intergranular corrosion and pitting corrosion, which is not desirable.

In addition, 8i (silicon) is added as a deoxidizing agent to avoid the influence of oxygen in the welding atmosphere when forming a weld, but Si also stabilizes the welding arc and improves the acid resistance of the weld. It has the effect of improving the chemical properties of
The effect can generally be expected at 180% or higher.However, if the SI content exceeds 1.5%, deterioration of toughness and corrosion resistance will occur, so the upper limit is 1.50%.vjt
The desirable range of the 8i content is 07 to 095.

Furthermore, like 8i, Mn (manganese) is also added as a deoxidizing agent, and at a content of 1.10 or more, it stabilizes the γ layer and has an adverse effect due to the contained 8 (sulfur). effective in preventing In addition, Mn
If the amount exceeds 2.60%, corrosion resistance will deteriorate, so addition of more than that should be avoided. In particular, the preferable addition range for the Mn content is L7 to 195%.

Note that Mn and 81 must be added in such a ratio that the content ratio of Mn/8i is in the range of 1.3 to &O1, preferably 1.8 to 2.8.

If the content ratio of M n / Si is less than 1.3, the cracking resistance will deteriorate and cracks will easily form in the welded part, and if the content ratio of M n / Si is less than 80. When you start to exceed 8 and O, which will be explained later.
This is because the effect of addition cannot be fully exhibited.

S is an important element having important significance in the present invention.
Sulfur (sulfur) normally forms a low-point compound during solidification of a weld and is said to cause weld cracking, but according to the inventors' study, such S , 1008% to 0050%, it has become clear that bead shape and blowhole resistance can be effectively improved without causing weld cracking or deterioration of corrosion resistance. The preferable range of S is QQO8 to αo25eI2, and the more preferable range is 001 to Q02%. Such a range further emphasizes the effect of adding S.

In addition, 0 (oxygen) contributes to the stability of the welding arc and the improvement of the bead shape, and in order to fully exhibit such effects, it is necessary to contain it in a proportion of at least α0050% or more. However, if it exceeds 0,040%, hot and cold workability deteriorates, so the content range is 10,050 to 0,040%, preferably 0,035% or less, more preferably 0,080% or less, particularly preferably is 0010 to QO2(l).

In addition, nickel (Ni) is the main element of welding wire,
From the viewpoint of stabilizing the γ layer, improving toughness, and improving corrosion resistance, it is necessary to contain nickel in a ratio of at least ao1 or more.The upper limit of nickel is that it may deteriorate the weld cracking property or cause wire rods to deteriorate when used in large quantities. Since it is expensive, its upper limit is limited to about 2faO%.

In addition, Cr (chromium) is a main element added to Fe, which is the basic element, along with N1, and is an element that improves corrosion resistance and oxidation resistance. It is demonstrated in the ratio, but 82
Since adding more than 1% will cause problems of high-temperature embrittlement such as σ phase precipitation, it is generally added at a ratio of 12 to 82%.

Furthermore, N (nitrogen) is an element normally contained in stainless steel, and a certain amount of it can improve toughness and stabilize the R layer, but if its content increases, the bead shape will deteriorate. Therefore, its content must be kept at 0.06% or less.

In the present invention, such predetermined elements are blended and contained in specific proportions, and the remainder is Fe (iron) and unavoidable impurities (
For example, P, Al, etc.) are used to construct the welding wire rod, thereby improving the bead shape at the welded part, that is, avoiding protrusion of the bead and making it possible to create a relatively flat bead shape. In addition, the stability of the welding arc was improved, and blowhole resistance was also improved. In particular, the welding wire according to the present invention is suitably used as a welding wire in MIG welding and TIG welding of stainless steel.

Furthermore, the welding wire according to the present invention may contain MO (molybdenum) in a proportion not exceeding 5% in order to improve high-temperature strength, corrosion resistance, and pitting corrosion resistance as necessary. Note that addition of a large amount of MO is undesirable because it causes high temperature embrittlement and deterioration of toughness. Also, Cu (copper)
MO can also be contained in a proportion of 5% or less, which improves corrosion resistance, but the effect becomes even more remarkable when combined with the above-mentioned MO. This Cu
If a large amount of T is contained, problems such as high-temperature embrittlement and deterioration of hot workability will occur.Furthermore, T.
(H↑'7) is added as a deoxidizing agent and has the advantage of improving intergranular corrosion resistance, so it can be added and contained in a proportion not exceeding 1%. but,
Addition of Ti exceeding 1% is not desirable because problems such as high-temperature embrittlement and deterioration of pitting corrosion resistance occur. Further, Nb (optional) is added in a proportion not exceeding 1% in order to improve high temperature strength and intergranular corrosion resistance. Note that addition of a large amount of Nb causes problems such as high-temperature embrittlement and deterioration of weld cracking properties, which is not preferable. Moreover, these Mo, Cu, Ti, and Nb can be added in combination, but when two or more of these types are added, it is desirable that the total amount does not exceed 7%.

Furthermore, in the present invention, in particular, the welding wire according to the present invention having the above-mentioned chemical composition further includes 1Mg of Ca (calcium).
By adding at least one of (magnesium), B (boron), and REM (rare earth element), the peeling of slag that occurs in the weld zone and the
, 0,8i, and Mn in predetermined amounts can be further improved. Furthermore, such Ca, Mg, B.

REM also contributes to improvements in hot workability, weld cracking resistance, high-temperature strength, etc. In order to achieve these effects, even if one or more of the above elements are used, it is desirable that they be used in a proportion that does not exceed 0.5% in total.

It should be noted that if Ca, Mg, etc. are added or contained in a total amount exceeding 0.5%, problems such as deterioration of hot workability and unstable welding arc occur, which is not desirable.

Examples will be shown below to more specifically explain the present invention, but it goes without saying that the present invention is not limited in any way by the description of the examples. Note that the percentages in the examples are expressed on a weight basis unless otherwise specified.

Example 1 Stainless steel having the composition shown in Table 1, with the remainder being iron and unavoidable impurities, was melted in a 2-ton melting furnace, then a steel ingot was produced, and then forged and rolled according to conventional methods. Then, wire drawing was performed to obtain a welding wire with a wire diameter of 1.2 mm.

Using various welding wires having different compositions thus obtained, arc welding was performed under the downward welding conditions shown in Table 2 and the vertical upward fillet welding conditions shown in Table 3. We evaluated the bead shape generated. Note that the bead shape value (I (/W) is the value indicated by the reinforcement height H relative to the bead width (W)), and normally, under the downward welding conditions in Table 2, the value (I (/W) is The bead shape is considered to be good when α) is smaller than o and aoo, and in the case of vertical advance fillet welding in Table 3, the bead shape is considered to be good when the value (β) is smaller than 0.250. There is.

Further, regarding the evaluation of plowhole weld cracking, arc welding was performed under the conditions shown in Table 4, and the evaluation was performed.

For evaluation of corrosion weight loss, test pieces were taken using the method of JI 5-Z-8321 after welding under the conditions shown in Table 4, and test pieces were taken using the 5% 2S04 test method according to JIS-G-0591. I asked for it.

Table 5 summarizes the results thus obtained, ie, wire workability, wire shape values (α, β), weld cracking resistance, blowholes, and corrosion weight loss.

As is clear from the results in Table 5, the number 19 according to the present invention
All of the welding wires No. 29 to 29 not only have good wire strength, but also excellent bead shape, i.e., excellent bead width, even under downward welding conditions and vertical upward fillet welding conditions. The height of the excess buildup was small, there were no weld cracks or blowholes, and even if there was corrosion loss, the numerical value was low, indicating good corrosion resistance.

On the other hand, wires with ff11 to 18, which are commercially available materials or comparative materials that differ from the composition of the present invention, have some kind of problem, such as poor bead shape, weld cracks, blowholes, or corrosion loss. Name because I have a problem.

Table 2 Table 8 Table 4 Table 5 Table 5 Example 2 Welding wires were produced from stainless steel having various component compositions shown in Table 6 below, the balance being iron, according to the method of Example 1. Thereafter, wire workability, bead shape, weld cracking, blowholes, and corrosion weight loss were evaluated according to the evaluation method of Example 1, and the results are shown in Table 7 below.

As is clear from Table 7 below, copper and molybdenum are further added to the welding wire having the composition according to the present invention.

It can be seen that the corrosion weight loss is significantly improved by adding at least one of titanium and niobium.

Example 3 Various welding wires were produced from stainless steel having the alloy composition shown in Table 8 below according to the method of Example 1,
Furthermore, welding was performed using the various welding wires according to the method of Example 1, and various characteristics were evaluated, and the results are shown in Table 9 below.

In this example, the effect of adding REM, Mg, Ca, and B(7) was observed, and the effect of adding elements such as molybdenum was also investigated.

As is clear from the results in Table 9, REM, Mg.

It can be seen that by blending at least one of the elements Ca and B, the stability of the arc is improved, and the area ratio of the slag is reduced, and the peelability of the slag is significantly improved. A: 1. In addition, when molybdenum is added, as demonstrated in Example 2, the corrosion loss value is significantly reduced and corrosion resistance is improved.

Claims (1)

[Claims] (1) By weight, C: 0.20% or less, 5iHQ8
0-1.50%, Mn: 1.10-2.60%,
Ni: fiO~2&0%, Cr: 12.0~B2
．． ．． 0%, S20, 008-0050%, 0:0005
0~0040%, N: 0.06% or less, and the content ratio of Mn/SI is within the range of 1.3~&O, with the balance being Fe and inevitable impurities. Excellent weldability. stainless steel welded wire rod. (At 21 weight, MoX less than ao%, C less than 50%%
uX l, Nb of 04 or less, and Ti (1.0% or less), which further contains at least one type (however, if two or more types are contained, the total amount thereof is 7% or less) Claims The welding wire rod according to item 1. (31 heavy gt Te, C: (, 20% or less, 8i: Q80
~1.50%, Mn: 1.10~2.60%, Ni
H60~2FLO%, Cr: l 2.0~82.
0%, S: QO08~0050%, 0: O, OO
50~(1040chi, N: 0.06% or more), and the content ratio of Mn/8i is within the range of 1.3~&0, and is selected from the group consisting of 13XCaXMg and rare earth elements. A stainless steel welding wire rod with excellent weldability, containing at least one of the following elements in a proportion not exceeding 0.5%, and the remainder consisting of Fe and unavoidable impurities. (4) MO15.0% with an MO of 50% or less by weight. The following Cu
, 1.0% or less Nb and 1.0% or less Tl,
The welding wire according to claim 3, further comprising at least one type (however, if two or more types are contained, the total amount thereof is 7% or less).